Search

In this work, the scCO2 modified by mixture of water and ethanol was used for a preparation of crystalline and pure nanostructured TiO2 thin films in one step processing. All the experiments were performed over precursor titania thin films prepared by reverse micelles assisted sol-gel method, using hardly removable nonionic surfactant Triton X-114, however, forming uniform nano-domains. The effect of temperature (40-150 °C), pressure (10-30 MPa), modifier composition \n(20, 50 and 80 % w/w of water in ethanol) and concentration inscCO2 (5-15 wt. %) and consumed amount of solvent (50-200 g) on microstructure and purity\nof TiO2 thin films was thoroughly studied by means of Raman spectroscopy, X-ray diffraction, and contact angle measurements.

This work is focused on a study of TiO2 aerogel SFC with scCO2 modified by mixture of ethanol and water in a ratio 1:1. The effect of temperature (40-100 °C), pressure (10-30 MPa) and modifie concentration in scCO2 (5-15 wt.%) and the additional drying with pure CO2 on microstructure, purity and textural properties of TiO2 aerogel was investigated. Processed monoliths were characterized by XRD analysis, Raman spectroscopy and N2 physisorption.

This contribution is accomplished by the study of the membrane affinity via contact angle measurements and by structural analysis via electron he transport properties of the TFC PA were studied at various experimental conditions and the obtained results will be discussed.

In the present study, the effect both of the botanical source and proportion of starch produced from agricultural surplus on the microstructure properties of starch/chitosan/glycerin films was tested. Effective gas transport properties gas diffusion transfer was performed. Starch/chitosan/glycerol biodegradable films were obtained by casting method from giant squid (Dosidicus gigas) pen chitosan mixed with glycerin and starch. Four starch samples were prepared using exceeding or low quality biomass including broken rice grains, hard yellow corn surplus, banana surplus form exportation activity and low quality cassava in three different weight proportion (chitosan/starch) corresponding to 1/1, 2/1 and 5/1. Extraction of starch from the raw material was carried out by mixing it with a water solution of sodium disulfite (5 wt.%). Afterwards, the obtained suspension was filtered and then decanted at 5°C for 24 h. The obtained starch was washed repeatedly with distilled water and ethanol (96 vol.%). Finally, the starch samples were dried at 55°C for 48 h, crushed and sieved. It was found that the gas diffusion transport properties significantly depend on the starch source used. Differences in diffusion transport rates through the films prepared with different starches are related to the size and distribution of granules of starch in the films and/or the amylose conten.

The present work deals with the crystallization of monolithic TiO2 aerogels in environment of pure and water modified scCO2. To remove organic precursors used during sol-gel synthesis and to crystallize TiO2 the combination of several steps with pure and watermodified scCO2 was tested with respect the high porosity and the specific surface area of titania blocks.

In this work, the method using pure and modified supercritical carbon dioxide was tested to prepare a set of crystalline TiO2 thin films deposited on soda-lime glass. Precursor solution for TiO2 films was prepared by a templated sol-gel method in the reverse micelle environment. Simple approach or combination of several steps performed at different temperature (40-150 °C) and solvent composition was applied at pressure 30 MPa. Water, ethanol and water : ethanol (1:1) mixture were added into supercritical CO2 as modifiers at concentration 10-30 wt.%. The effect of extraction design on microstructure and purity of TiO2 thin films were examined.

Extrakce čistým a modifikovaným superkritickým oxidem uhličitým (SFE) a extrakce podkritickou vodou byla využita k získání krystalických a čistých nanostrukturních tenkých filmů TiO2 a současně k odstranění organických prekurzorů ze syntézy solu sol-gel metodou. Při SFE byl sledován vliv teploty a použitého modifikátoru (vody, metanolu, etanolu a acetonu) na čistotu a mikrostrukturu tenkých filmů TiO2. Byl testován i kombinovaný postup extrakce, kdy se střídaly kroky s CO2 modifikovaným vodou a s CO2 modifikovaným organickými rozpouštědly. Čistota a krystalinita tenkých filmů byla zjištěna pomocí Ramanovy spektroskopie. Fázová složení a velikosti krystalů anatasu, žádané krystalické struktury, byly vyhodnoceny rentgenovou difrakční analýzou (XRD).